6.1 KiB
meow
CLI app helper
Features
- Parses arguments
- Converts flags to camelCase
- Negates flags when using the
--no-
prefix - Outputs version when
--version
- Outputs description and supplied help text when
--help
- Makes unhandled rejected promises fail hard instead of the default silent fail
- Sets the process title to the binary name defined in package.json
Install
$ npm install meow
Usage
$ ./foo-app.js unicorns --rainbow
#!/usr/bin/env node
'use strict';
const meow = require('meow');
const foo = require('.');
const cli = meow(`
Usage
$ foo <input>
Options
--rainbow, -r Include a rainbow
Examples
$ foo unicorns --rainbow
🌈 unicorns 🌈
`, {
flags: {
rainbow: {
type: 'boolean',
alias: 'r'
}
}
});
/*
{
input: ['unicorns'],
flags: {rainbow: true},
...
}
*/
foo(cli.input[0], cli.flags);
API
meow(helpText, options?)
meow(options)
Returns an object
with:
input
(Array) - Non-flag argumentsflags
(Object) - Flags converted to camelCase excluding aliasesunnormalizedFlags
(Object) - Flags converted to camelCase including aliasespkg
(Object) - Thepackage.json
objecthelp
(string) - The help text used with--help
showHelp([exitCode=2])
(Function) - Show the help text and exit withexitCode
showVersion()
(Function) - Show the version text and exit
helpText
Type: string
Shortcut for the help
option.
options
Type: object
flags
Type: object
Define argument flags.
The key is the flag name and the value is an object with any of:
type
: Type of value. (Possible values:string
boolean
number
)alias
: Usually used to define a short flag alias.default
: Default value when the flag is not specified.
Example:
flags: {
unicorn: {
type: 'string',
alias: 'u',
default: 'rainbow'
}
}
description
Type: string | boolean
Default: The package.json "description"
property
Description to show above the help text.
Set it to false
to disable it altogether.
help
Type: string | boolean
The help text you want shown.
The input is reindented and starting/ending newlines are trimmed which means you can use a template literal without having to care about using the correct amount of indent.
The description will be shown above your help text automatically.
version
Type: string | boolean
Default: The package.json "version"
property
Set a custom version output.
autoHelp
Type: boolean
Default: true
Automatically show the help text when the --help
flag is present. Useful to set this value to false
when a CLI manages child CLIs with their own help text.
This option is only considered when there is only one argument in process.argv
.
autoVersion
Type: boolean
Default: true
Automatically show the version text when the --version
flag is present. Useful to set this value to false
when a CLI manages child CLIs with their own version text.
This option is only considered when there is only one argument in process.argv
.
pkg
Type: object
Default: Closest package.json upwards
package.json as an object
.
You most likely don't need this option.
argv
Type: string[]
Default: process.argv.slice(2)
Custom arguments object.
inferType
Type: boolean
Default: false
Infer the argument type.
By default, the argument 5
in $ foo 5
becomes a string. Enabling this would infer it as a number.
booleanDefault
Type: boolean | null | undefined
Default: false
Value of boolean
flags not defined in argv
.
If set to undefined
the flags not defined in argv
will be excluded from the result.
The default
value set in boolean
flags take precedence over booleanDefault
.
Example:
const meow = require('meow');
const cli = meow(`
Usage
$ foo
Options
--rainbow, -r Include a rainbow
--unicorn, -u Include a unicorn
--no-sparkles Exclude sparkles
Examples
$ foo
🌈 unicorns✨🌈
`, {
booleanDefault: undefined,
flags: {
rainbow: {
type: 'boolean',
default: true,
alias: 'r'
},
unicorn: {
type: 'boolean',
default: false,
alias: 'u'
},
cake: {
type: 'boolean',
alias: 'c'
},
sparkles: {
type: 'boolean',
default: true
}
}
});
/*
{
flags: {
rainbow: true,
unicorn: false,
sparkles: true
},
unnormalizedFlags: {
rainbow: true,
r: true,
unicorn: false,
u: false,
sparkles: true
},
…
}
*/
hardRejection
Type: boolean
Default: true
Whether to use hard-rejection
or not. Disabling this can be useful if you need to handle process.on('unhandledRejection')
yourself.
Promises
Meow will make unhandled rejected promises fail hard instead of the default silent fail. Meaning you don't have to manually .catch()
promises used in your CLI.
Tips
See chalk
if you want to colorize the terminal output.
See get-stdin
if you want to accept input from stdin.
See conf
if you need to persist some data.
See update-notifier
if you want update notifications.
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